Reactions involving the hydrogenation of CO, e.g., Fischer-Tropsch (F-T) synthesis to produce hydrocarbons, are complex and produce many stages. As a consequence, this necessitates the use of multicomponent, polyfunctional catalysts; catalysts constituted of a supported catalytic metal, or metals, component, e.g., an Iron Group metal such as cobalt, which may be modified or promoted with an additional metal, or metals, e.g., rhenium. (Periodic Table of the Elements, Sargent-Welch Scientific Company; Skokie, Ill. Copyright 1979). Reaction occurs between the feed components, on contact with the catalytic metal, or metals, component and its oxide, reduction of the oxide (which may be reduced only with difficulty), and support component. Knowledge of these reactions is largely empirical, requiring the accumulation and correlation of large amounts of experimental data covering various parameters including not only the composition of the catalyst but also its method of preparation. Trial-and-error methods outstrip theory in the development of catalysts; and these methods are based on more than one hundred years of process developments utilizing catalysts.
Early F-T catalysts were formed by compositing Group VIII or Iron Group metals with kieselguhr, e.g., (100 wt. parts Co per 100 wt. parts kieselguhr), and additionally 20 wt. parts of an oxide of a Group VIIB metal, e.g., Mn, to improve the activity and yield of higher molecular weight hydrocarbons at higher reaction temperature. Further improvements in the development of F-T catalysts resulted in the use of ThO.sub.2 (optimum 18 wt. parts per 100 parts Co) instead of MnO.sub.2, and then to the replacement of part of the ThO.sub.2 by a Group IIA metal oxide, MgO, while doubling the kieselguhr content to produce a commercial form of the catalyst (100:5:8:200).
Typically, in preparing catalysts for conducting F-T synthesis reactions, a Group VIII metal, preferably with an additional metal, e.g., a Group VIIB or VIII metal, or metals, to modify or promote the activity of the catalyst is composited with a particulate refractory inorganic oxide solids component by impregnation techniques. For example, cobalt may be first impregnated onto an alumina, silica, or titania support from a solution in which a soluble compound or salt of cobalt has been dissolved, and then a promoter metal, e.g., platinum, similarly added; or, cobalt and platinum can be coimpregnated onto a support from a single solution containing soluble compounds or salts of both cobalt and platinum. The metals impregnated support is then shaped, dried, calcined, and the metals component then reduced to activate and complete formation of the catalyst. These catalysts have considerably less activity than desired, and very low selectivity in producing hydrocarbon wax. Gas production is higher than is desirable. Consequently, there is need of a process for producing catalysts of these compositions but which have higher activity and improved selectivity.